1. Field of the Invention
The present invention relates to a method and apparatus for transferring pallets around an end terminal in a conveyor assembly, which includes a roller disc secured to a sprocket so that a clutch sprocket of the pallet is trapped between the roller disc and a multi-strand chain at the end terminal for pallet transfer.
2. Background Art
Prior art conveyor assemblies rely upon friction devices, such as pressure rollers, friction discs, wedge-type discs, or spring-loaded wedge plates, for transferring pallets around a terminal end of a conveyor. These devices are subject to wear because the load is primarily supported by a friction interface, and the interface itself is subject to wear.
As the weight of the carriers or pallets increases due to the size of each and the weight of the attached tooling, which often includes nest fixtures, as well as the hinging of multiple pallets to create a pallet train, the subject wear of those designs relying on friction becomes much more critical. When wear occurs, the carriers or pallets may slip while being transferred around a sprocket at a terminal end of a conveyor chain, which may result in the slamming of pallets after the slippage, or may result in the carriers or pallets not having sufficient frictional engagement to travel through the terminal end to raise the carrier or pallet from the lower level to the upper level of the conveyor.
Accordingly, it is desirable to provide an improved conveyor assembly in which pallets or carriers may be transferred around a sprocket at a terminal end of the conveyor assembly without relying upon frictional engagement, while maintaining ability of pallets to stop and accumulate along horizontal runs of the conveyor at dedicated stop stations as the endless chain continues to rotate.
The present invention overcomes the limitations of prior designs and provides the user of the invention a positive transfer of carriers or pallets on either terminal end of a conveyor using a rolling sprocket mechanically trapped between rotating roller chain rollers. The invention eliminates the concern over wear restrictions thereby increasing the load carrying capacity of the carrier or pallets.
The carrier or pallets are fitted with sprockets which provide resistance to the chains by means of adjustable clutches and alignment bars which prevent skewing of the carrier or pallets beyond an acceptable tolerance. The sprockets are engaged on the bottom side of the upper multi-strand roller chain and the alignment bars are riding on the top side of the upper multi-strand roller chain.
The multi-strand roller chain is driven by a pair of drive sprockets located at the drive end of the conveyor. At the opposing end of the conveyor similar sprockets act as idler and/or take-up sprockets to allow for proper tensioning of the multi-strand roller chain.
Attached to each sprocket is a disc containing rollers of like type and material as the multi-strand roller chain. The disc maintains a matching pitch of the driven and the idler sprockets. The distance between the circumferential pitch diameter of either type of sprocket and the roller disc is such to allow for the carrier or pallet sprocket to become xe2x80x9ctrappedxe2x80x9d between the two during the transfer around the terminal ends of the conveyor.
Accordingly, an object of the invention is to provide an improved method and apparatus for transferring pallets around a sprocket at a terminal end of a conveyor assembly in a manner which eliminates the reliance upon frictional engagement for the end transfer, and in a configuration which maintains the ability of the pallets to stop and accumulate along the horizontal runs of the conveyor at dedicated stop stations while the chain is continuously moving.
The above object and other objects, features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.